Symbol SE 923, Integration Manual

Page: 199 / 238

A-3
Serial Interface Specification
Figure A-1 shows the decoder and host signal relationships.
Figure A-1. Decoder and Host Signals
The Decoder
This section describes the requirements that are specific to the decoder.
Transmitting Data
When the decoder needs to send information, it must first check the CTS line to see if the host
is trying to transmit.
Once the bus is available, the decoder may transmit. The decoder is responsible for:
• any programmed intercharacter delays
• retrying if the host communicates during decoder transmission.
Table A-2. . Host Signal Lines
HOST RXD Serial data receive input. Driven by the serial data transmit output of the decoder.
HOST TXD Serial data transmit output. Drives the serial data receive input of the decoder.
HOST CTS Decoder transmit request (input). See The Host on page A-6.
HOST RTS Decoder transmit request granted (output). See The Host on page A-6.
TXD Host RXD
RXD Host TXD
RTS Host CTS
CTS Host RTS
Host Decoder